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Buzz after installing stereo 98 Sebring infinity system
I installed an aftermarket stereo because I was tired of repairing the volume knob on my oem unit. I used a wiring harness, soldered all wires properly and I’m 100% certain it’s wired correctly. I’m hearing a weird buzzing sound that sound like PWM when I turn on my headlights. It changes how it sounds when I adjust brightness of the dash light. Also, the left rear speaker doesn’t sound right. Overall it’s very loud it just has these weird quirks. I’ve installed many stereos and build some huge systems with multiple amplifiers back in the day. This is the first attempt at reusing a factory amp. (Which didn’t turn on until I hooked up the blue wire. I also validated the crazy factory wiring scheme actually matches what the wires do. See this url: https://static.cargurus.com/images/site/2011/02/15/10/17/pic-8840657694446619062-1600x1200.jpeg so https://cimg6.ibsrv.net/gimg/www.chr...29cd2a2800.jpg https://cimg8.ibsrv.net/gimg/www.chr...9122064a4.jpeg |
Facepalm. It's staring me right in the face on that diagram. The amplifier audio circuits are grounded through the stereo. Notice there are no ground wires specifically designated for the amplifier section? The head unit has one. Just because the amp is 'connected to metal' doesn't mean that the negative wire for the speakers share the same ground path. The original head unit completely provides the audio ground for the entire system. The new head unit uses a floating ground (like most do) which isolates the entire thing from noise, but in this case, does nothing but generate tons of it. My aftermarket head unit was never designed to provide any sort of ground through the speakers (voltage would just go to an electrically isolated speaker using + and -). It wouldn't be an issue to use a floating ground in this case because the circuit is already at high power (no chance of picking up sound and amplifying it directly to a speaker).
I could go on, but... All i have to do is pick one of the speaker (-) wires and connect it to ground on the wiring harness. The white / black wire (left rear negative) provides the cleanest ground (maybe it IS the ground in the scheme of things). Connecting this to chassis ground eliminates the entire problem. No buzz, and the slight alternator whine is gone as well. |
Or it could be the bent pin in the connector that wasn’t completing the (-) connection for left rear. Even bigger facepalm but much easier fix. |
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